Aircraft: EMB ERJ 170/175 ER/LR
Phase of flight: Cruise
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance

After the plane had pushed back from the gate; operations in the departure station called the coordinator and informed him that the load report they had given the captain was incorrect; that the bag count as actually 66 bags and not 64 bags. The captain was immediately notified via ACARS of the miscount and it was believed the issue was resolved. A few minutes later; departure station operations calls the coordinator again; this time saying the cargo load was incorrect; that it was 1;806 lbs. more than reported on the load report. Coordinator asks what the correct load is; and they said it was actually 4;046 lbs. At this time I go to message the Captain again to tell him not to take off and realized the plane was already airborne. I inform the captain that the load report is off by at least 1;800 lbs. and tell him to contact me via Radio so we can go over his numbers to calculate the actual Center of Gravity (CG) of the aircraft. While I am verbally discussing with the Captain about the initial load report; trying to calculate the new CG and verifying if the aircraft is handling within limits; we both questioned the new reported cargo weight as it exceeds the aft bin limit. The Captain informed me that he had tried several times before takeoff to verify the final load report with the rampers and ops in the departure station. Another Dispatcher contacts the departure station operations and verifies the amount to be 4;046 lbs. Since this both exceeds the max limit of the cargo hold and therefore prevents an accurate CG of being calculated; and since the CG will move farther aft as the fuel in the wings gets lower; the coordinator and myself felt the flight was no longer safe and I messaged the Captain to divert to a nearby airport since it was the nearest suitable airport. The Captain asked me to verify I wanted him to divert now and I replied yes; that station ops was already informed and provided him with weather and ops freq. As the flight diverted; I calculated the actual payload on the aircraft and provided it to the Captain. Although the cargo been exceeded max weight; the aircraft did not land over max landing weight. The pilot landed without incident. The divert station ops verified the bags to have been 62 bags and 4 heavy bags totaling 70 bags with the cargo being 2;668 lbs.I suggest better communication between operations and flight crew. Operations could have radioed the flight crew immediately as going through dispatch about a significant error caused a delay in relaying the information to the pilots. This event started prior to closing the door. The ramp personnel asked the First Officer during his walk around if we could accommodate a load of freight weighing a total of approximately 2;000 lbs. He instructed them to wait on loading until he could confirm the load could be safely accommodated. When he returned to the ramp; the cargo was already loaded in the aft compartment and he was told it was actually only approximately 1;000 lbs. When we received the Cargo Load Report; it indicated total load of 59 standard and 5 heavy bags in forward cargo and 1;071 lbs. freight loaded in aft cargo compartment. We ran the reported load and received an ACARS report stating to move 4 passengers from section 'C' to section 'A' to adjust Center of Gravity (CG) index within limits. We did this; ran new load with passengers moved and received good takeoff performance numbers. After closing the door; the tug driver said they'd made a mistake and that we should add 1 standard bag to forward compartment and the actual weight in rear cargo was 2;208 lbs. I asked twice to clarify these numbers since his English was poor and I wasn't satisfied with his confidence in his count. We ran new numbers anyway; and adjusted once again the passengers per the ACARS instruction. All at the same time; after already being instructed to push the aircraft 'tail west' and telling the tug driver twice to stop the push; he pushed aircraft tail east. We disconnected with the approval of ramp and I decided to call ops before moving to confirm the load numbers. After a few minutes; I was told by someone claiming to be the Ramp Manager via ops frequency; that the second numbers I had received were in fact accurate. So we taxied out. Just prior to reaching the runway; we received message from dispatch stating to once again add 2 bags to the forward cargo. We did this received numbers; and we're cleared for takeoff. The takeoff seemed normal. After being airborne for what I think was approximately 30 minutes; Dispatch informed us that; yet again; the departure station ops called and stated the load actually being 4049lbs in rear cargo. This was obviously an exceedance to the cargo compartments weight limitations. At this point I contacted dispatch via Atlanta Radio and discussed the prior events and had them run performance with new numbers. They informed me that the CG was outside limits. They called departure station ops again to confirm the weight; and then instructed me that the 4049lbs was accurate and we should divert to a nearby airport. I concurred. We began this process; I [notified ATC] and instructed [them] of our intent; briefed FA's and Passengers and descended into the divert airport. I updated the ZFW in computer and realized I could burn enough gas off to prevent overweight landing; so I did. We touched down at approximately 74;000 lbs. Landing was uneventful. Arriving at the gate we had ramp personnel remove and weigh all cargo from rear compartment and also verify the contents of the forward compartment as well. The actual contents of both compartments were: 62 standard/4 heavy forward and 3;592 lbs. in the rear compartment. I made a write up in the aircraft mx logbook for the weight exceedance in the rear cargo and did not reload any of the rear cargo. We departed with only the bags in the forward compartment without any further complications.Ramp personnel should have received more training. Don't think they're aware of the dangers of overloading an aircraft. An ERJ-175 Captain questioned operations before takeoff about the weight and balance accuracy and was given a revision. Inflight Dispatch advised the crew of an error and later diverted them because the load was off at least 1;800 lbs. The cargo compartment weight limitations were exceeded.